System and method for controlling a vehicle battery pack based on estimated open circuit voltage

A system for an electrified vehicle (EV) having a battery pack includes a vehicle controller configured to charge and discharge the battery pack according to power limits defined at activation of the EV by an estimated open circuit voltage (OCV). The estimated OCV is based on voltages measured for a duration after a last deactivation of the EV, at least one temperature measured after the last deactivation, and a decay parameter that is a function of the voltages measured and detected using a selected relaxation time and an iterative estimation of a sub-parameter of the decay parameter.